Method of heating fluids and apparatus used therefor



CZ.- W. STRATFORD METHOD: oF HEATING FLUIDs AND APPARATUS USED 'mEREFoR Filed Dec .r

10-. 1926,A 3, Sheets-Sheet'- l mm. .M

Oct. 21, 1930. c.' w. sTRATFoRD METHOD OF HEATING FLUIDS AND APPARATUS USED-THEREFOR Filed Des. 10. 192s s'shevefts-sheet 2 v fr METHOD 0F HEATING FLUIDs AND APPARATUS USED THEREFOR 3 Sheets-Sheet 5 Filed no.

. 30 order that an eilicient heat exc Patented o1..21',. 1930 l CHARLES WALOOTT STBATFORD, OF SAN FRANCISCO, G AJLfIIEOIBZlWIA.l

METHOD OF HEATING FLUIDS AND APPARATUS USED THERFOR 'applic-atan mea December 10, 1926. serial No.'153,9o3.

This invention relates to improvements in methods of heating fluids and apparatus used therefor 'as particularly adapted vto the heat treatment of hydrocarbon oils, either to raise the oil to a distillation temperature or to4 a temperature sutcient to brin about cracking of the hydrocarbons heate In the distilling branch of petroleum refining, it is usual practice to heat petroleum or its distillates for the purpose of distillation or cracking in shell stills or pipe stills.

. These methods entail the use of shell stills, either batch or continuous in operation positioned over furnace settings, the heat of fuel combustion being transmitted'to the oil by radiant heat or heat of convection. Likewise in pipes heat is transmitted from the combustion of fuel to. thel oil circulated through tubes or pipes.

- Recognizing the-diiculties and ineiliciencies of these methods and equipment I propose a'furnace setting. in which are vertically positioned cylindrical heating tubes, the combustion gases being circulated around these heating tubes consecutively while the"oil is progressively advanced through the tubes in' I anopposed direction to the passage of the combustion gases. The oil in the cylindrical heating tubes is rotated at a higlh velocity in ange will be effected between the combustion gases and the liquid oil.

Fig. 1 is a diagrammatic view of an oil heating system, showing the arrangement ofthe heating cylinders and the manner in which theyare connected into the s stem.

v Fig. 21s an enlarged detai of the furnacev setting. *Y

Fi 3 is a view taken along the line 3-3 `in Fig. 2.

Fig. 4 is a sectional view of one of the c ylinders in which theliquid is spun at high velocity. l

Fig. 5 is a view taken along the line 5-5 in Fig. 4, and n Fig. 6 is a. View taken along-the 11ne6-6 in Fig. 4.'

Referring to nated'a furnace setting .conslstmg of sepathe drawings, at 1 is desigrate heating chambers, 2, '3, 4 and 5, sepa-v rated by battle walls 6, 7 and 8. The furnace 1s preferably heat-ed by oil or gas burners, not shown, the combustiongases, however, being introduced tangentially through thel fiues 9 into thebottom of the chamber 2, so that they will proceed in a spiral course upwardly through the chamber, this course of the combustion gases being determined by the pitch of the initial velocity of injection' and combustion expansion, and if needed, spiral baffles may be placed in the walls of the chamber, to produce spiral circulation of the gases. From the chamber 2 the combustion gases pass by aduct through the baffle wall 6, entering the second chamber 3 tangentially. Therein they are directed in a spiral course downwardly around the heating cylinder positioned in this chamber. The combustion gases pass from the lower part of the chamber 3 and follow acourse in the chamber 4, similar to that in the chamber 2. From the top of the combustion chamber 4 the partially cooled combustion gases pass downwardly over a bank of preheating Atubes 9 positioned in the chamber 5. The combustion gases are finally discharged through a flue 10, shown' A in Fig. 1.

The oil to be treated is withdrawn from the storage tank 11 and directed by means of a pump 12 through 'a heat exchanging device 13, Where its temperature is raised by heat transfer with a hot oil taken from a later stage .in the system. After preheating/the oil is passed through the line 14 to a flash or vaporizing chamber 15, the preheating of the oil being sufficient to drive oil' the lower boiling point fractions or lighter oils from the hydrocarbon products being treated. This vaporization or distilling off of the lighter lfractions may be accompaniedby a reduction in pressure produced by means of the regulating Valvel in -the-line 14.

The vapor-ized material is taken oi overhead through the f line 17 and is passed through a condenser or rectifying stage, not 95 shown, and reduced to a-liquid distillate.

The unv'aporized oil is drawn oil' through the line 18, controlled bya valve 19 and is picked up by the pump 20v by .which it is discharged through the line 21 into the pre- 100 heating coils 9. ln the bank of preheating coiis its temperature is again raised l brought in heat exchange relation 'with the combustion gases passing through the chamber After circulation through e preheating coils 9 the oil is directed a line 22 into the top of the first heating tube 23; the circulation through WLch wilt be hereinafter described in more detail. om the tube 23 the oil passes through the liuc 2li to the tube 25 thence through line 23 to the tube 27 and finally is disel arged through the line 28 into the vapor flash chamber 29. A valve 30 el in the iine for reducing the presen;L stne `xieated oil, if desired.

the heating of the oii i ,i i heat exchange is produc t pressure is maintained upon 'the .t vaporization insofar is vvell ltnovvn fact that a b exchange can be edected between bustion gases and liquid, than Wi rial. in vapor form.

Un discharge into the vaporiaing or chamber 2C* flash the lighter fractions are distilled off due to the reduction in pressure, and to the contained heat in the oil, the volatile material passing overhead through the line 3l and the un porized material passing down through the line 32 controlled by a valve 33 to the pump 34, Where it may be returned through the line 35 to the heat en" changer 13, being discharged through line 36 or diverted from the system. through the line 37, controlled by a valve 33. elise, a portion of the oil may be recirculated through the heat exchanger, and a portion diverted from the system according to the desires of the operator. y

Referring, novv, to the particular design of the heating tubes', and the method used for rotating the liquid column at a high velocity in the respective heating tubes. ln describing the details of the tube construction a single'tube Will be explained, but it is understood that the tubes are identical.

In Figures 4, 5 and G, at the to of the tube shell 23 is connected by bolted anges a top vassembly 39. The oil discharged from the preheating coil is introduced into the top by means of the pipe 22. rllhe oil passes through the center of the tube in a column o'r enclosed pipe 40, and is delivered into the rotor of a centrifugal pump el, mountedupon the shaft 42, which is directly connected with the motor 43, positioned on bottom of the tube. Each of the cylinders 23, 25 and 27 are equipped with a motor of identical construction. The rotor picks up the oil from the vertical column and discharges it at high velocity from the extremity of the rotor vanes, thus imparting to the column of oil in the tube a high rotative speed.

In the top of the tube are spiral vanes 4A vvhich allow the spinning liquid to freely pas? and again enter the suction pipe i0 through 'the duct e6, and also to be partly discharged through the port 45, the latter having connection with the succeeding heating tube or final iiash chamber. A liquid is returned through the ducted to combine with the oil being introduced. To assure the highest rate of heat transfer through the tube and into the oil column the hot spinning liquidvviil be rotated a speedabove that required for high turbulence at the point Where the iiquid meets the heated surface. rllhis vviil normaily be in the order of twenty (20) to t ty (30) feet per second on the heated sur- As the oil is heated its specific Weight decrease relative the oil in the center be this rise in temperature, and ifugai force Will bring about radial circuit. ion from the center of the tube to the heated surface.

'the nziain circulation of the oil is dou/'nvvardly through the central pump suction tube et), through the pump rotor which imparts rotative movement to the discharged oil. rlhis discharged oil forms a rapidly rotating liquid column surrounding the pump suction tube and having a relatively slovv rate of vertical travel. rllhis rate of Vertical flow may be varied to meet operating requirements. The entire heating tube is at all times con-- pletely hlled vvith oil.

rlhe combustible mixture to be burned in the combustion chambers is as described injected tangentially into the combustion chambers which give a high rotative effect to the total gas volume during combustion, promoting rapid mixing and eflicient combustion. ./ilso the passage ofthe gases of combustion at high velocity over the outer heating surfaces of the tubes improves the rate of heat transfer. The high temperature of the Walls of the combustion chambers promote a rapid rate of heat transfer through the heating tubes by radiant heat trahsmitted-radially from the Walls to the heating tubes or cylinders. Heat from the gases of combustion in the second and third combustion chambers is transmitted principally by radiation and convection, and by convection through the chamber containing the preheater coil bank. The velocity of the gases of combustion through the combustion and heating chambers is maintained as high as that necessary for the best heat transfer.

It has been found by experimentation with commercial apparatus, comprising a single l 4The mechanical energy expended in driving the pump rotoris utilized to impart high velocity of oill over the heating surface maintaining high turbulence and mixing within the li uid column. The operation of the entire eating system comprising preheaterv in oiger conditions necessary .for the highest rate of heat transfer per unit area. It will be understood that other methods ,y may be employed for spinning the liquid in the cylinder than the use of a rotor fin the lower part of the tube. Satisfactory results have been obtained by tangentially introducing the liquid simultaneously at the up-l per and lower ends of the cylinder to rotate the liquid. Also, the liquid may .be rotated by ineans of a paddle immersed over a part or full' length of theheating tube and driven by an outside 'motore as is the kcentrifugal pump or rotor. The construction shown is but a singleoper'able method of rotating 'the I liquid column to produce the desired heat exchange between the circulating liquid and the combustion gases passing through the combustion chambers surrounding the liq-l uid spinning cylinders. Furthermore, 1n

,place of the motors 43any driving means may be usedito rotate theoi .l

As a substitute for the spinning liquid column the liquid circulation in the'heating tubes may be accomplished by effecting a continuous vertical fiow'though and around a stationary open endedtube positioned 'co- 4axially within a hollow heating cylinder, the inlet and discharge being connected to the top'or upper part ofthe cylinderf 1 I. claim as n1y`in-vention:

l. A cyclicv -system for heating liquids ,comprising the steps of introducing the liqv'uid to pass in a straight-line lineal flow to an energy source, converting the lineal flow of the liquid at the lener source to -spinning, spiral rotation, su sequent-ly .reconverting the spinning energy -to lineal flow land recycling a portion of the liquid to the energy source and removing a portion o f the liquid while heating the outer surface of the spinning liquid body.

2. A cyclic system for heating i' Vliquids comprising the steps of introducing lthe liqliquid body.

uid to pass in a straight-line lineal flow to an energy source, converting the lineal flow vof the liquid at the energy source to spinning spiral rotation, subsequently reconverting the spinning energy to lineal flow and recycling afinajor portion" of the liquid to the energys'ource and removing a minor portion of the liquid while heating the outer surface of the spinning liquid body.

3. A cyclic system for heating liquidscomprising the steps of continuously introducing the liquid to pass in a straight-line lineal flow to an energy source, converting the lineal flow of the liquid at the energy'source to spinning, spiral rotation, subsequently re-l converting the spinning energy to lineal flow and recycling a portion of the liquid to the` energy source, and continuously removing a portion of the liquid -while heating the outer surface ofthe spinning liquid body.

4.' A cyclic system for heating liquids comprising the steps of introducing the liquid to pass in a straight-line lineal lowto an energy source, ,converting the lineal flow of thev liquid at the energy source to spinning, spiral rotation to travel in an Opposite direction A and for substantially the,V distance of the lineal How, subsequently reconverting the spinning energy tolineal flow and recycling a portion of the liquid to the energy source,

'and removing a portion of the liquid while heating the outer'surface-of the spinning liql uid body;

5. A cyclic system for heating liquids comi prising the steps of passing the liquid in a straight-line lineal fiow to a source of. energy,

vconverting thel lineal flowv of the liquid at thesource of energy to spinning spiral rotation, said `rotation adapted to advance in an opposedv direction and for substantially the distance of the lineal flow and in heat exchange relation. therewith, reconverting the splnning energy to lineal 'flow and recycling e a portion of the liquid to the source of energy, 11o

and removing a portion of the liquid while heating the outside surface of the spinning 6. Ahydraulic `relatively smaller diameter and means for introducing liquid to the inner tube, a source of energy for converting the 'lineal low of the liquid 4to spinning rotation in the annular space surrounding the inner tube, means for reconverting the spinningenergy to straightline flow and recycling aportion of the liquid machine for heating liquids comprising an outer casing, an inner tube of' to the energy source, and separate means for I removing yaA portion of the'v liquid continuously.

7. A hydraulic machine 'forheating liquids comprising an outer casing, an inner tube of relatively smaller diameter, vmeans for introducing liquid into the inner tube, a source of energy ositioned vat the opposite end of thev inner tu e from the inlet fbrconverting lineal .o

iiow of the liquid to spinning rotation ii annuler space surrounding lire inner menne :idgecent the inlet for reeonifer'ling lspinning' energy to straight llow for recycling a portion of the liquid 'lo lie energy source, and separate ineens lor removi b e portion of the liquid continuously.,

8. A connected series of oyelie steps for heating liquids, each step comprising die introduction of a feed liquid to pese in straightline lineal flow to an energy Source end dhere being converted to spinning spiral rol ,1j reconverting the spinning energy 'lo lineal flow While recycling e portion of the liquid to the energy source and removing i por-filon oln the liquid to be circulated through Ylie subsequent steps, and heating elle outer sui-*faces oi the spinning liquid loodies.

9. A cyclic system :lor heating liquids Coniprising the steps of introducing 'the liquid lo 'pass in a struighbline lineal low lo en energy source, converting the lineal of the liquid at the energy source to spinning spirel roletion, conserving a portion oi 'lhe unspenfi; energy of elle spinning liquid loy recireulelion9 adding the conserved energy to (Llfie linee-il flow portion of the Cyclic stream., end removing e portion of the liquid lWhile healing Irhe outer surface of the liquid loody.

A l0. A cyclic system for healing liquids com prising elle steps oi inirodueing {3h-e liquid :to pass in a straight-line lineel ilow to en energy Source, converting the lineal llorv oi liquid at the energy Source 'lo spinning spiral rotation, conserving a portion ol3 the unspenl; energy of tlie spinning liquid loy recirculation of a major portion thereof end adding ille conserved energy to the lineal Elow portion of the cyclic stream, and removing e niinor portion of the liquid While healing the outer surface oi the spinning liquid loody.

CHARLES WALCOTT STRATFRD. 

